1. Field of the Invention
The invention relates to automatic hardware presses of the type utilized to press fasteners into sheet metal, and relates particularly to an automatic hardware press that incorporates safety features for the protection of the operator and the tooling used with such presses.
2. Description of the Prior Art
The below-listed U.S. Pat. Nos. are known to exist:
______________________________________ 1,648,296 2,387,478 2,400,486 2,438,837 2,767,819 2,858,930 3,240,310 3,258,106 3,275,120 3,288,267 3,315,049 3,487,182 3,803,898 3,521,735 3,578,142 3,866,004 3,907,099 3,938,245 3,939,314 4,060,160 4,075,961 4,236,302 4,348,806 4,391,358 4,395,641 4,676,421 4,699,261 4,739,873 5,086,965 5,191,960 ______________________________________
Other patents known to exist include Japanese Patent 0262718 issued December, 1985, and Japanese Patent 0124417 issued June, 1986.
It is noted that U.S. Pat. No. 4,391,358 and 5,191,960, listed above, are owned by the assignee of the instant invention.
U.S. Pat. No. 4,391,358, owned by the assignee hereof, addresses the problem of operator safety, and provides a means for retracting the press ram if the operator's finger or any other part of the operator's body intervenes between the ram and the workpiece. Operatively, circuit means are provided to sense when electrical contact occurs between the upper and lower tooling. It is one of the objects of the present invention to provide an operator and tool protection system that expands and improves on the method and apparatus disclosed in this previous patent.
The installation of hardware into sheetmetal assemblies has, in the past, been a process that can result in damaged tooling when a fastener, for instance, fails to completely enter an automatic tool. Accordingly, it is another object of the present invention to provide a method and apparatus that senses the improper positioning of the fastener and deactivates the press to thereby prevent damage to the tooling.
Another disadvantage of some hardware insertion presses is that they sometimes shear off a portion of a mispositioned fastener intended to be inserted into the sheetmetal workpiece, and then press the sheared off portion of the fastener into the workpiece in the area where the complete fastener was intended to be inserted. It is therefore another object of the present invention to provide an automatic hardware insertion press that senses misplacement of the fastener, inhibits shearing of the fastener, and inhibits the imposition of pressure on a misplaced or sheared fastener, thus preventing damage to the workpiece, which would otherwise have to be reworked or scrapped, with attendant expense.
Automatic insertion presses operate on a cyclical basis in which the ram to which the upper tooling is attached reciprocates between a retracted upper position and a lower "press" position to place the upper tooling in cooperative association with the lower tooling to "insert" or press the fastener into an appropriate aperture in the workpiece by the application of pressure on the fastener. In the press described in U.S. Pat. No. 4,391,358, an electrical circuit, including a switch associated with the upper tooling, normally senses and responds to electrical contact between the upper and lower tooling. As a consequence thereof the ram is permitted to impose insertion pressure on the fastener. It should be noted that the spacial position of the upper tooling in relation to the lower tooling in this prior patent is not critical to the imposition of insertion pressure. Thus, insertion pressure may be applied at any point along the excursion path of the ram if electrical continuity between the upper and lower tooling is sensed.
If the circuit does not sense electrical continuity between the upper and lower tooling, as when an electrically non-conductive impediment, such as a finger or hand, is interposed between the upper and lower tooling, the imposition of a non-injurious light pressure on the upper tooling by non-electrical contact with the impediment actuates the switch associated with the upper tooling and the circuit that controls imposition of insertion pressure by the ram is interrupted and the ram returns to its retracted position without imposing insertion pressure on the impediment. It is therefore a still further object of the present invention to provide means for adjustably defining a predetermined press "window" constituting an adjustable spacial relationship between the upper and lower tooling only within which the ram may be driven by insertion pressure, but which even within the press "window" the ram may still be retracted if the upper tooling encounters a non-electrically conductive impediment.
A still further object of the invention is the provision of a press which exerts insertion pressure only within a predetermined press "window", and which provides for the retraction of the ram if the pressure on the tooling builds up to a predetermined level either before or after the specified range defined by the press "window" within which the fastener is intended to be installed.
For universal application of the automatic press of the instant invention to press "hardware" regardless of the material from which the hardware is fabricated, i.e., electrically conductive or electrically non-conductive, means are provided for selectively actuating to "open" condition the pressure sensitive switch associated with the ram so as to override the safety feature that causes the ram to retract when the upper tooling encounters an electrically non-conductive impediment, while still retaining the adjustable means by which the press "window" is defined.
Yet another object of the invention is the provision of an automatic hardware insertion press wherein the means for defining the press "window" may be selectively deactivated.
One of the problems often encountered in automatic hardware insertion presses, which are inherently subjected to vibration during use, is proper alignment (or intentional misalignment) of the upper tooling mounted on the ram in relation to the lower tooling on which the workpiece is supported. Accordingly, a still further object of the present invention is the provision of a press incorporating means for securing the lower tooling in a manner that facilitates alignment of the upper and lower tooling, or intentional misalignment thereof when required by special circumstances.
During use, the tooling of a press must occasionally be removed and replaced with different tooling to accommodate different types of fasteners or workpieces. With conventional presses, it is sometimes very difficult to mount the original tooling in precisely the original position to thus enable accommodation of a previous workpiece. It is therefore yet another object of the invention to provide a mounting means for the lower tooling that is adjustable in relation to the axis of travel of the upper tooling whereby precise repeated placement of the lower tooling may be accomplished quickly and accurately.
The invention possesses other objects and features of advantage, some of which, with the foregoing, will be apparent from the following description and the drawings. It is to be understood however that the invention is not limited to the embodiment illustrated and described since it may be embodied in various forms within the scope of the appended claims.